Sensitivity Analysis of Soil Treatment Systems including Surcharge and Vacuum and PVDs

Document Type : Original Article


1 PhD candidate, Department of geotechnical engineering, Estahban Branch, Islamic Azad University, Estahban, Iran

2 Associate professor, Department of Water Engineering, Faculty of Agriculture, Shiraz University, Shiraz, Iran

3 Associate professor, Department of geotechnical engineering, Estahban Branch, Islamic Azad University, Estahban, Iran

4 M.Sc. student, Department of geotechnical engineering, Estahban Branch, Islamic Azad University, Estahban, Iran


In Finite element modelling (FEM) of the soil treatment systems that includes prefabricated vertical drains (PVDs), either for preliminary designation, or in the evaluation period, one the main challenges of geotechnical engineers are the correct estimation of the parameters used in the model. The main objective of these kind of soil treatment is the acceleration of the consolidation process to reinforce the weak soft clay stratum underneath. In the consolidation process the initial soil parameters changes, such as void ratio, hydraulic conductivity, swelling and compression index and so on and that is why the modelling of such reclamation process is so challenging. In previous published literature, there was no paper, especially concentrate on the sensitivity analysis. In this literature first, a case history is presented and verified, and then base on the verified model, the following parameters as: void ratio, vacuum pressure, phi and over consolidation ratio, rate of loading of the surcharge embankment, mesh size, Lambada (𝝀) and Kappa (𝜿), Hydraulic conductivity ratio and Mesh type were parametrically investigated. It was shown that, even a minute change in the quantity of some parameters can adversely affect the precision of the prediction of the model. The results of this study can be used by both field and design engineers, involved in the construction of embankments on soft ground for soil treatment systems in weak and rate-sensitive clays.


1- Nicholson, D., and Jardine, R., 1981, Performance of vertical drains at Queenborough bypass, J. G., 31, 1, 67-90.
2- Shang, J., Tang, M., and Miao, Z., 1998, Vacuum preloading consolidation of reclaimed land: a case study, J. C. G. J. , 35, 5, 740-749.
3- Gao, C., 2004, Vacuum preloading method for improving soft soils of higher permeability, Ground improvement, 8, 3, 101-107.
4- Yan, S., and Chu, G. I., 2003, Soil improvement for a road using the vacuum preloading method, 7, 4, 165-172.
5- Qian, J., Zhao, W. B., Cheung, Y., and Lee, P. J. C., 1992, The theory and practice of vacuum preloading, Geotechnics, 13, 2, 103-118.
6- Muhammed, J. J., Jayawickrama, P. W., Teferra, A., Özer, M, 2020, Settlement of a railway embankment on PVD-improved Karakore soft alluvial soil, I. J. Technology, 23, 5, 1015-1027.
7- Chai, J. C., and Miura, N. G., 1999, Engineering, Investigation of factors affecting vertical drain behavior, J. J. o. G., 125, 3, 216-226.
8- Chai, J. C., Shen, S. L., Miura, N., and Bergado, D. T., 2001, Simple method of modeling PVD-improved subsoil, J. J. o. g., 127, 11, 965-972.
9- Vu, V. T., Yang, Y. Y., and Vu, A. T., 2021, Effect of permeability variation in vacuum consolidation, J. G. E., 51, 4, 130-134.
10-Nguyen, T. N., Bergado, D. T., Kikumoto, M., Dang, P. H., Chaiyaput, S., and Nguyen, P. C., 2021, A simple solution for prefabricated vertical drain with surcharge preloading combined with vacuum consolidation, Journal of Geotextile and Geomembranes, 49, 1, 304-322.
11- Indraratna, B., Zhong, R., Fox, P. J., & Rujikiatkamjorn, C. J., 2017, Large-strain vacuum-assisted consolidation with non-Darcian radial flow incorporating varying permeability and compressibility, Journal of Engineering Geology and Geotechnical Engineering, 143, 1, 04016088.
12- Deng, Y., Kan, M. E., Indraratna, B., & Zhong, R. B., 2017, Finite element analysis of vacuum consolidation with modified compressibility and permeability parameters, I. J. G. G. Engineering, 3, 2, 1-13.
13- Indraratna, B., Sathananthan, I., Rujikiatkamjorn, C., & Balasubramaniam, A. J., 2005, Analytical and numerical modeling of soft soil stabilized by prefabricated vertical drains incorporating vacuum preloading, I. J. G., 5, 2, 114-124.
14- Rujikiatkamjorn, C., Indraratna, B., & Chu, J. J., 2008, 2D and 3D numerical modeling of combined surcharge and vacuum preloading with vertical drains, I. J. G., 8, 2, 144-156.
15- Chai, J. C., Shen, J. S. L., Liu, M. D., & Yuan, J. C., 2018, Predicting the performance of embankments on PVD-improved subsoils, Geotechnics, 93, 222-231.
16-Pardsouie, M. M., Pardsouie, M. H., Zomorodian, S. M. A., Mokhberi, M., 2022, Application, Numerical Study of Efficiency of the Vacuum Preloading in Weak Clay Treatment (a case study), J. J. C. E., 6, 2, 1-10.
17- Bergado, D. T., Jamsawang, P.,  Jongpradist, P., Likitlersuang, S., Pantaeng, C., Kovittayanun, N., & Baez, F., 2022, Case study and numerical simulation of PVD improved soft Bangkok clay with surcharge and vacuum preloading using a modified air-water separation system, J. G. Geomembranes, 50, 1, 137-153.
18- Pardsouie, M. M., Pardsouie, M. H., 2022, The effect of PVDs length on the lateral displacement of embankments, J. G. G., 18, 1, 655-658.
19- Bergado, D. T., Balasubramaniam, A., Fannin, R. J., & Holtz, R. D., 2002, Prefabricated vertical drains (PVDs) in soft Bangkok clay: a case study of the new Bangkok International Airport project, J. C. G. J., 39, 2, 304-315.
20- Bergado, D. T., Chai, J., Miura, N., & Balasubramaniam, E., 1998, PVD improvement of soft Bangkok clay with combined vacuum and reduced sand embankment preloading, A. J. G. , 29, 1, 12-25.
21-Madaschi, A., Gajo, A., 2017, one-dimensional viscoelastic and viscoplastic constitutive approach to modeling the delayed behavior of clay and organic soils, A. J. A. G.,12, 4, 827-847.
22-Asaoka, A., Nakano, M., Noda, T., & Kaneda, K. J. S., 2000, Delayed compression/consolidation of natural clay due to degradation of soil structure, Foundations, 40, 3, 75-85.
23-Pardsouie, M. M., & Pardsouie, M. H., 2022, The importance of incorporating hydraulic modifier function versus step loading in ground improvements including vacuum preloading, Advance Researches in Civil Engineering, 4, 2, 54-60.
24-Tarefder, R., Zaman, M., Lin, D. G., Bergado, D. T., 2009, Finite element modeling of soft ground with PVD under vacuum and embankment preloading, I. J. G. E., 3, 2, 233-249.
25- Indraratna, B., Sathananthan, I., Rujikiatkamjorn, C., & Balasubramaniam, A.,2005, Analytical and Numerical Modeling of Soft Soil Stabilized by Prefabricated Vertical Drains Incorporating, Vacuum reloading.
26- Gouw, T. L., & Gunawan, A., 2020, Vacuum preloading, an alternative soft ground improvement technique for a sustainable development, in:  IOP Conference Series: Earth and Environmental Science, IOP Publishing, 012003.
27- Rowe, R., & Taechakumthorn, C., 2007, The counteracting effects of rate of construction on reinforced embankments on rate-sensitive clay, in:  Proceedings of the 5th International Conference on Earth Reinforcements IS Kyushu, Citeseer.
28- Rowe, R., & Li, A. L., 2002, Behaviour of reinforced embankments on soft rate-sensitive soils, J. G., 52, 1, 29-40.
29- Magnani, H., Almeida, M., & Ehrlich, M. I., 2009, Behavior of two reinforced test embankments on soft clay, J. G., 16, 3, 127-138.
30- Hinchberger, S. D., & Rowe, R. K., 2003, Geosynthetic reinforced embankments on soft clay foundations: predicting reinforcement strains at failure, J. G. Geomembranes, 21, 3, 151-175.